The present invention relates to a miniature structures fabrication tool and process. Particularly, this invention relates to a material delivery system for enabling an additive Direct Write process in fabrication of complex circuits or structures on different substrate compositions.
Further, the present invention relates to a material carrier element and associated mechanisms for enabling a wide variety of materials to be precisely positioned at a required distance from the substrate for subsequent Direct Write Forward Transfer process.
The present invention additionally relates to miniature structures fabrication tools capable of operating in a xe2x80x9cDirect Writexe2x80x9d mode of operation and in a xe2x80x9cMicromachiningxe2x80x9d mode of operation. In the xe2x80x9cDirect Writexe2x80x9d mode of operation, the material carrier element is positioned in an intercepting position with an energy or energetic beam for ablating the deposition layer of the material carrier element for subsequent transfer of the ablated material to the substrate. In the xe2x80x9cMicromachiningxe2x80x9d mode of operation, the material carrier element is displaced from the energetic beam path so that the energetic or energy beam impinges directly onto the surface of the substrate for ablating, evaporating, melting, cutting, drilling, or otherwise removing material therefrom in a patterned fashion.
The present invention further relates to a miniature structure fabrication tool and technique in which actuation/deactuation of the source of energy and change of relative interposition between the source of energy, material carrier element and the substrate is carried out in a precisely synchronized manner.
Miniature structures having electrical components are widely used in a variety of consumer and industrial items. Such miniature structures have been found to provide advantages both in performance and price. This has resulted in different manufacturing tools and techniques being developed for fabrication of a variety of complex circuits and structures.
Among those techniques, a Direct Write process has been developed which is an additive process generally implemented as Laser Forward Transfer, Matrix Assisted Pulse Laser Evaporation, or Laser Induced Forward Transfer.
Additive structures created by the Direct Write processes may include optical, chemical, biological, environmental, physical, electromagnetic detectors/sensors, mechanical elements, electromagnetic elements, and a wide variety of passive electronic components. The Direct Write processes are applicable to a wide variety of materials and often use a laser beam as an ablating source of depositable material with subsequent transfer of the ablated material towards the surface of the substrate for deposition thereon.
Another well-known process used in fabrication of miniature structures is laser micromachining in which a laser beam impinges upon a substrate for ablating the surface of the substrate to create various vias, holes, xe2x80x9cMicromachiningxe2x80x9d mode of operation. In the xe2x80x9cDirect Writexe2x80x9d mode of operation, the material carrier element is positioned in an intercepting position with an energy or energetic beam for ablating the deposition layer of the material carrier element for subsequent transfer of the ablated material to the substrate. In the xe2x80x9cMicromachiningxe2x80x9d mode of operation, the material carrier element is displaced from the energetic beam path so that the energetic or energy beam impinges directly onto the surface of the substrate for ablating, evaporating, melting, cutting, drilling, or otherwise removing material therefrom in a patterned fashion.
The present invention further relates to a miniature structure fabrication tool and technique in which actuation/deactuation of the source of energy and change of relative interposition between the source of energy, material carrier element and the substrate is carried out in a precisely synchronized manner. channels, etc. on the surface of the substrate.
Typically, fabrication of miniature structures, especially of the complex circuits, requires for both additive and subtractive processes to be used on the same workpiece. In conventional fabrication tools, the workpiece has to be transferred between the area where the additive process takes place and the area of the subtractive process.
During the transference between the subtractive and additive areas, the workpiece may be subjected to physical damage, contamination, or re-oxidation of areas freshly exposed during the micromachining process. Additionally, transferring the workpiece from one area to another requires multiple alignments of the substrate, source of the depositable material and the laser in each area.
If only one of these disadvantageous effects is seen on the workpiece a resulting miniature structure created thereon may fail to meet performance requirements, thus decreasing yield of the manufacturing process. To somehow reduce influence of unwanted possible contamination, reoxidation or misalignment, additional measures are usually taken which increase the cost of the resulting microstructures and of the manufacturing process.
Therefore, a new fabrication tool and technique free of disadvantages of the conventional systems is long needed in the miniature structures manufacturing industry.
It is an object of the present invention to provide a fabrication tool and technique for manufacturing of miniature structures using a unique material delivery system which incorporates a material carrier element capable of intercepting an energy beam in an additive mode of operation and also is capable of being displaced from interception with the energetic beam in a micromachining mode of operation.
It is a further object of the present invention to provide a material delivery system in which the material carrier element has a backing element supporting a deposition layer having at least one, but possibly a plurality of distinct depositable materials, each of which is exposed to an energy beam in a predetermined sequence as required by the particular technological process.
It is another object of the present invention to provide a material delivery system in which a control unit coordinates relative disposition between the source of energy, substrate, and the material carrier element with actuating-deactuating of ablating radiation in a patterned and synchronized fashion.
It is still another object of the present invention to provide a plurality of distinct types of material carrier elements in combination with advancing mechanisms which allow for precise motion control, full automation and effective use of the depositable material.
In accordance with the present invention, a material delivery system for miniature structures fabrication tool includes a substrate, a material carrier element having a deposition layer, an energy beam directed towards the material carrier element, a control unit for changing relative disposition and for exposing respective areas of the deposition layer to the energy beam in a patterned fashion.
Upon exposure of the deposition layer to the energy beam, the depositable material at a predetermined area is ablated and transferred to the substrate for deposition thereon at the respective regions corresponding to the ablated areas of the deposition layer.
The material carrier element (which may be any of the following types: tape, ribbon, disk, pad, etc.) includes a backing element supporting the deposition layer thereon.
Preferably, the material carrier element is maintained in parallel relationship with the substrate at a distance not greater than 25 microns. During the additive mode of operation of the fabrication tool, the control unit changes relative locations between the energy beam and the material carrier element in either of three fashions: scanning of the energy beam over the material carrier element, manipulating the material carrier element with regard to the energy beam, or the combinatorial motion of the energy beam and the material carrier element.
It is important that the deposition layer of the material carrier element includes at least one, but preferably a plurality of distinct depositable materials located at predetermined zones on the material carrier element. As required by the particular technological process, the control unit aligns the energetic beam with a respective one of the zones containing different depositable materials.
The energy beam may be either a laser beam, preferably ultraviolet (UV) laser beam, an ion beam, or an electron beam. The control unit controls the size and the shape of the cross-section of the energetic beam for adjusting size and shape of the written features.
The fabrication tool of the present invention is capable of being operated either in a Direct Write (additive) mode of operation or micromachining (subtractive) mode of operation. In the Direct Write mode of operation, the material carrier element is positioned in an interception path with energy beam, while in the micromachining mode of operation, the material carrier element is displaced away from interception with the energy beam, thus allowing direct access of the energy beam to the substrate for ablating the surface. It is preferred that in micromachining mode of operation a fluence of the energetic beam is at least 1 J/Cm2.
There are several types of material carrier elements used in the material delivery system of the present invention. One of them is a xe2x80x9cCDxe2x80x9d type material carrier element which is a disk supported on an air table having a flat surface perforated with orifices through which air (or other gas) is forced outward under the pressure. Thus, the disk material carrier element is supported on a thin gaseous cushion. The disk material carrier element is rotated on a thin gaseous cushion (the rotation is carried out with low friction forces and self-stabilizing in the direction normal to the surface) at a rate determined by both the energy beam repetition rate and the radial distance of the source of energy from the disk center in order to pack the radiation ablated xe2x80x9cholesxe2x80x9d in the deposition layer as tightly as possible to provide maximization of material utilization.
Simultaneously, in conjunction with rotational motion, the disk material carrier element slides in parallel relationships over the surface of the substrate. The substrate is capable of being displaceable independently of the sliding disk material carrier element. Pulsing of the source of energy is synchronized with the substrate motion resulting in tracing a spiral pattern of laser xe2x80x9cfootprintsxe2x80x9d on the material carrier element until the material of the deposition layer is completely expanded in a highly efficient manner.
Another type of material carrier element used in the material delivery system of the present invention is a tape material carrier element where opposite ends are supported on a xe2x80x9ctake-upxe2x80x9d reel and a xe2x80x9csupplyxe2x80x9d reel by which the tape material carrier element is transported in either of two directions.
Over the substrate, the tape material carrier element is received and is guided by the tape guide unit which supports the tape material carrier element a predetermined distance above the substrate and which is capable of moving the tape position up to several mm. in a direction normal to the tape travel and parallel to the substrate surface in order to access parallel xe2x80x9ctracksxe2x80x9d of the tape material.
Preferably, the tape material carrier elements are encased or housed in cassettes which are convenient to ship, handle, store, and which are protected from external contamination.
These and other novel features and advantages of this invention will be fully understood from the following detailed description of the accompanying drawings.